llvm-6502/include/llvm/Linker.h

//===- llvm/Linker.h - Module Linker Interface ------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LINKER_H
#define LLVM_LINKER_H

#include <string>

namespace llvm {

class Module;
class LLVMContext;
class StringRef;

/// This class provides the core functionality of linking in LLVM. It retains a
/// Module object which is the composite of the modules and libraries linked
/// into it. The composite Module can be retrieved via the getModule() method.
/// In this case the Linker still retains ownership of the Module. If the
/// releaseModule() method is used, the ownership of the Module is transferred
/// to the caller and the Linker object is only suitable for destruction.
/// The Linker can link Modules from memory. By default, the linker
/// will generate error and warning messages to stderr but this capability can
/// be turned off with the QuietWarnings and QuietErrors flags. It can also be
/// instructed to verbosely print out the linking actions it is taking with
/// the Verbose flag.
/// @brief The LLVM Linker.
class Linker {

  /// @name Types
  /// @{
  public:
    enum LinkerMode {
      DestroySource = 0, // Allow source module to be destroyed.
      PreserveSource = 1 // Preserve the source module.
    };

  /// @}
  /// @name Constructors
  /// @{
  public:
    /// Construct the Linker with a previously defined module, \p aModule. Use
    /// \p progname for the name of the program in error messages.
    /// @brief Construct with existing module
    Linker(Module* aModule);

    /// Destruct the Linker.
    /// @brief Destructor
    ~Linker();

  /// @}
  /// @name Accessors
  /// @{
  public:
    /// This method gets the composite module into which linking is being
    /// done. The Composite module starts out empty and accumulates modules
    /// linked into it via the various LinkIn* methods. This method does not
    /// release the Module to the caller. The Linker retains ownership and will
    /// destruct the Module when the Linker is destructed.
    /// @see releaseModule
    /// @brief Get the linked/composite module.
    Module* getModule() const { return Composite; }

  /// @}
  /// @name Mutators
  /// @{
  public:
    /// This method links the \p Src module into the Linker's Composite module
    /// by calling LinkModules.
    /// @see LinkModules
    /// @returns True if an error occurs, false otherwise.
    /// @brief Link in a module.
    bool LinkInModule(
      Module* Src,              ///< Module linked into \p Dest
      std::string* ErrorMsg = 0 /// Error/diagnostic string
    ) {
      return LinkModules(Composite, Src, Linker::DestroySource, ErrorMsg);
    }

    /// This is the heart of the linker. This method will take unconditional
    /// control of the \p Src module and link it into the \p Dest module. The
    /// \p Src module will be destructed or subsumed by this method. In either
    /// case it is not usable by the caller after this method is invoked. Only
    /// the \p Dest module will remain. The \p Src module is linked into the
    /// Linker's composite module such that types, global variables, functions,
    /// and etc. are matched and resolved.  If an error occurs, this function
    /// returns true and ErrorMsg is set to a descriptive message about the
    /// error.
    /// @returns True if an error occurs, false otherwise.
    /// @brief Generically link two modules together.
    static bool LinkModules(Module* Dest, Module* Src, unsigned Mode,
                            std::string* ErrorMsg);

  /// @}
  /// @name Implementation
  /// @{
  private:
  /// @}
  /// @name Data
  /// @{
  private:
    Module* Composite; ///< The composite module linked together
  /// @}

};

} // End llvm namespace

#endif